I thought metal-rich deposition occurs due to oxygen dissociation in the Thermal deposition of metal oxide.
The degree of dissociation of a metal oxide depends on its affinity for oxygen (the Gibbs energy of oxide formation). The most stable oxides such as Al2O3, ZrO2, MgO, CaO, TiO2, rare earth oxides and others do not dissociate even at very high temperatures and very low oxygen partial pressure. Other oxides, such as CuO, NiO, CoO, MoO3, WO3, PbO, and others, easily dissociate at relatively low temperatures and high oxygen pressures. You can find the stability of one or another oxide depending on the conditions (temperature and partial pressure of oxygen) in the Ellingham diagram.
Vadim Verlotski thank you, Is it good to maintain little oxygen partial pressure in the vacuum chamber during synthesis? If yes then how to calculate it?
Of course, it is useful to have a high oxygen partial pressure to prevent thermal dissociation of oxides in the furnace. The problem is that vacuum furnaces cannot operate in air or even in bad vacuum. In a vacuum chamber, such a partial pressure of oxygen is permissible at which there is no oxidation of the heaters, which are usually made of molybdenum, tungsten or graphite. You can consider this pressure to be equal to the maximum allowable residual pressure in a vacuum furnace, which is usually indicated in its technical data.
Sorry, but I do not understand the problem here. If you are concerned about sub-stoichiometric film deposition, then I have seen some researchers overcoming that by sintering the film in the presence of air.
In your question, you want to preserve the stoichiometric ratio of your source. If by the source you mean your target material, then a very thin layer would have been deposited, which you can easily buff.
Amod Kashyap, Is your second part of the answer independent of material selection? ( especially in the case of metal oxide deposition)
@Chandra Kharvi, I have never used a metal oxide as target but technically it should not. During sputtering there is a rise in cathode temperature, but we use regular supply of cold water to keep the cathode cool. Therefore, the rise in bulk temperature is not enough to form an oxide. However, due to regular electron bombardment the surface temperature can increase considerably and the effect will only be visible upto a few nano or micrometres on the surface depending on the duration of sputtering, which can be removed by slight buffing or using a 1000, 1200 grade emery sheet.
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